Known from USH1262 is the use of a video surveillance camera or CCTV (closed-circuit television), hardened against radiation, for monitoring the bowing of fuel assemblies. The camera is placed in a sealed housing and is moved vertically, underwater, along the assemblies to be characterized.
Such a monitoring method using an underwater camera is generally long to implement due to the volume and weight of the equipment to be installed, the remotely controlled movement of the camera along the fuel assembly, and the decontamination of the equipment after use.
This monitoring is done for example when a nuclear reactor is stopped, in order to replace some of the nuclear fuel assemblies. All of the assemblies are taken out of the core of the reactor. The spent assemblies are evacuated and replaced with new assemblies. The other assemblies are reorganized inside the core. The assemblies can be subject to distortion monitoring before being evacuated or before being replaced in the core of the reactor. The main purpose of this monitoring is to obtain data on the behavior of the fuel assemblies under radiation.